1. Field of the Invention
The present invention relates to a method of manufacturing a thin-film pattern on a substrate and, more particularly, to a method of manufacturing a large-scale mask pattern for use in etching on a large substrate.
2. Description of the Related Art
In a conventional method of manufacturing a thin-film pattern using the etching technique, a protection mask is generally formed by the photolithographic process. Such a conventional protection mask forming technique is disclosed in, for example, "Revised Integrated Circuit Engineering (1)" written by Yuzuru Nagata and Hisayoshi Yanai and published by Corona, from Page 89 to page 91.
FIGS. 6A through 6D schematically illustrate a thin-film pattern manufacturing process by the conventional technique.
In FIGS. 6A through 6D, reference numeral 10 denotes a substrate; 11, a thin film made of a conductor, a semiconductor or an insulating material; 12, a photosensitive organic resin layer; 12a, photosensitized portions; 12b, non-photosensitized portions; 13, a light-transmission type photo mask; 14, photoprotective portions of the photo mask 13; 15, a mask pattern; and 16, a thin-film pattern. The photosensitive organic resin layer 12 and the photo mask 13 are of the negative type.
For patterning the thin film 11, the thin film 11 made of a conductor, a semiconductor or an insulating material is first formed on the substrate 10 by an adequate means, as shown in FIG. 6A, and then a photosensitive organic resin is coated on the thin film 11 to form the photosensitive organic resin layer 12. Next, the photo mask 13 is located above and aligned with the photosensitive organic resin layer 12. After the alignment is completed, ultraviolet radiation (UV) is applied to the photosensitive organic resin layer 12 through the photo mask 13. At that time, since the photoprotective portions 14 of the photo mask 12 prohibit the passage of the ultraviolet (UV) ray, exposure of the photosensitive organic resin layer 12 to the ultraviolet radiation (UV) forms the photosensitized portions 12a and the non-photosensitized portions 12b in the photosensitve organic resin layer 12. Thereafter, the photosensitized portions 12a and the non-photosensitized portions 12b of the photosensitive organic resin layer 12 are subjected to a developing process which employs a developer, as shown in FIG. 6B. Since the solubility of the photosensitized portions 12a to the developer is lower than that of the non-photosensitized portions 12b, only the photosensitized portions 12a remain on the thin film layer 11 after the development process. The remaining photosensitized portions 12a form the mask pattern 15. Subsequently, the thin film 11 is subjected to the wet or dry etching process using the mask pattern 15 as an etching protective mask to remove the portions of the thin film 11 other than the portions thereof which oppose the mask pattern 15, as shown in FIG. 6C. Thereafter, as shown in FIG. 6D, the portions 12a of the mask pattern 15 are removed by a removing solvent or oxygen plasma to form on the substrate 10 the thin-film pattern 16 which is the same as the mask pattern 15.
Since the exposure condition of the photosensitive organic resin layer 12 largely affects the accuracy with which the photo mask 13 is transferred onto the photosensitive organic resin layer 12, when the photosensitive organic resin layer 12 is exposed through the photo mask 13, batch exposure of the resin layer 12 at a uniform illuminance is desired.
However, in the aforementioned conventional technique, there is a limitation to an increase in the size of the exposure device and it is thus difficult to enlarge the area on which batch exposure can be conducted. Hence, when the aforementioned mask pattern 15 is to be transferred onto the substrate 10 of a large area, the substrate 10 is divided into a plurality of areas, and exposure is conducted on each of these areas. That is, the mask pattern 15 is formed for each of the areas, and exposure is conducted on each of the areas. However, when exposure is conducted on each of the plurality of areas, the throughput of the manufacturing process is low and the joining accuracy of the adjacent mask patterns 15 deteriorates at the boundary of the adjacent areas.